Common Parasite Eggs Found in Fecals

Q. What species of parasites are identified in a fecal egg count test?

Cecelia, West Virginia

A. It depends on who is doing the count and the type of procedure used. If we’re just doing a typical fecal egg count using a technique like the McMaster’s, which is a common method, we’re mostly looking at (small and large strongyle) eggs.

We can’t differentiate between the large and small strongyle eggs—all of the eggs look the same, although we know from research studies from over a number of years that well over 99% of the eggs we see in a fecal sample are from small strongyles.

With that said, there are other parasite eggs you can see in the feces less commonly, such as tapeworms. However, a horse can be infected with tapeworms and you still won’t see the eggs in a fecal. Also, commonly in young horses, roundworm eggs seen during the fecal exam. And then, of course, there are some other less common parasites that you will occasionally see eggs from.

The eggs of these different parasites all look different, so if the person doing the count is well qualified, he or she will be able to identify the different species present.

About the Author

Ray M. Kaplan, DVM, PhD, Dipl. ACVIM, EVPC, is a professor of parasitology in the University of Georgia College of Veterinary Medicine's Department of Infectious Diseases. He served on the 2013 American Association of Equine Practitioner's Parasite Control Guidelines subcommittee.

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